Seed germination and seedling establishment of Cherimoya (Annona Cherimola mill.) at different temperatures

Cherimoya (Annona cherimola Mill.) has an exceptional flavor and aroma, which makes it a fruit with great potential. However, little is known about its propagation by seeds. According to the scientific literature, the germination of cherimoya seeds is affected much more by external conditions than by internal conditions. Germination of cherimoya variety ‘Concha Lisa’ were tested for germination at constant temperatures of 25, 30, 40°C, and at room temperature, varying from 20-25°C, coupled with total darkness. Seeds were sown in Petri dishes (0.8% agar water), for 25 days of incubation. The kinetics of germination was determined according to five closely related parameters, viz. final germination percentage (FGP), mean germination time (MGT), coefficient of velocity of germination (CVG), time to 50% germination (T50) and seedling length (SL). The temperature of 30°C was found optimally suitable with 70.8% FGP, 17.5 days MGT and 3.91 cm SL, while the room temperature of 20-25°C slightly improved germination with only 25% FGP. Furthermore, significant decrease in FGP and SL was observed at 25°C and 40°C of temperature in comparison to 30°C. The analysis also revealed that cherimoya seed germination, day 10-15 after seed sowing is suitable for final counts. An overview on the emergence of cherimoya seedlings, during a 12-week period in pots is presented

Morphological characteristics and seed germination improvement of two ecotypes of Astragalus armatus Willd. subsp. armatus in Algeria

Astragalus armatus Willd. subsp. armatus is an endemic shrub of the Northern Africa. Its cultivation and domestication are very limited because of difficulty with seed germination and establishment. In this study, we investigated some plant morphological characteristics in real time and in situ (leaves, fruit and seeds) of different ecotypes of A. armatus, collected from two sites in Algeria (Arid Steppe of Aïn Naga and Condorcet Mountain), which elevation and climate data are very different. Moreover, the role played by the seed coat in seed dormancy of these two different populations was tested by the effects of the pretreatment and its duration on the performance of seed germination, by considering the final germination percentage (FGP) and the mean germination time (MGT). These parameters are estimated for 10 days in Petri dishes and stored in darkness at (25°C). Pre-sowing treatments included immersion in concentrated sulphuric acid for 30, 60 and 90 min, and immersion in hot water (100°C) for 10 min. Statistical analysis showed that the treatment and the ecotypes effects on both FGP and MGT were highly significant (p< 0.0001). Untreated seeds of both ecotypes of A. armatus failed to germinate (except for a few of Condorcet Mountain ecotypes). For both populations, the most effective treatment was immersion in sulphuric acid for 60 min for the ecotype of Arid Steppe of Aïn Naga, and only 30 min for Condorcet Mountain. An excellent germinative strength is characterized by a higher FGP and a reduced MGT. The morphological characteristic and seed germination could be attributed to intraspecific variations resulting from the natural selection of the same species

Effect of cold stratification on seed germination of the multipurpose fruit shrub, Ziziphus Lotus (L.) Lam. (Rhamnaceae)

Shrubs and trees of the genus Ziziphus are a good example of naturally occurring multipurpose plant species with great potential in arid regions. This study was conducted to investigate the effect of cold stratification on seed germination and seedling growth of Ziziphus lotus (L.) Lam. Seeds were subjected to 0, 45, 90 and 120 days of cold stratification at 5°C. We also examined fruit, kernel and seed morphology. For each treatment period, four replicates of 50 seeds were incubated in plastic containers between two layers of moist sand at 15% and under greenhouse conditions for 15-day period. At the end of the experiment, the final germination percentage (FGP), shoot length and root length were assessed. The results clearly indicated that increasing duration of cold stratification improved seed germination. The most effective stratification period was 120 days where Z. lotus recorded 83% of FGP and 16.5 cm of total seedling length. Cold stratification treatments significantly increased shoot height, root length, as well as seedling total length. 120 days stratification treatment resulted in the highest shoot and root length (6.80 cm and 9.75 cm, respectively). An overview on the emergence of Z. lotus seedlings during a 15-day period was also illustrated

Seed germination and radicle establishment related to type and level of salt in common bean (Phaseolus Vulgaris L. Var. Djedida)

Saline soils contain multiple types of salt, each of them may exert a different effect on seed germination and seedling growth. The aim of this study is to assess the effects of five types of salt on the seed germination and radicle establishment of common bean (Phaseolus vulgaris L. var. Djedida). The experiment was set out as a factorial experiment based on completely randomized design with four replications of ten seeds for the seed germination and twelve replicates for the seedling growth. We used five kinds of salts (NaCl, Na2SO4, CaCl2, CaCO3 and KCl) with concentrations of 0, 100, 200 and 300 mM. Seeds were incubated in Petri dishes at 25°C, in the dark, for 10 days. The results of analysis of variance indicated that the effects of salt types and concentrations, and their interaction effect were significant in all measured traits (P< 0.01). However, no significance effect was found on secondary roots number and seedlings dry biomass with CaCO3 treatment solution. According to the results, the inhibitory effects of the five salt types differed significantly. Indeed, germination of common bean seeds by various salts were in the order of NaCl > KCl > CaCO3 > Na2SO4 > CaCl2. However, the taproot length, the number of secondary roots and the seedlings dry weight by various salts were in the order of CaCO3 > KCl > NaCl > CaCl2 > Na2SO4. The effect of salt concentration was also obvious. The reduction in dry biomass of cotyledons is proportional to germination rates and to the development of seedlings in dry biomass and in size. Seeds of P. vulgaris var. Djedida were able to germinate under all concentrations of the various types of salt. The lowest final germination percentage (FGP) was obtained under 300 mM of all salts recording the following values: CaCO3 - 60%, NaCl - 60%, KCl - 52.5%, Na2SO4 - 50% and CaCl2 - 27.5%. During germination stage, the radicle emergence would be controlled by the environment osmolarity, while the later growth of the seedling would be limited by the reserve mobilization

Seed germination and morphophysiological characterization of three tomato (Lycopersicon Esculentum) varieties irrigated with treated wastewater

The ability to reuse treated wastewater (TWW) would be of significant benefit to agriculture whilst at the same time providing a valuable water resource. This study concerned the effects of three various levels of treated wastewater (0%, 50% and 100% TWW) on seed germination and plant development of three different varieties of tomato (Lycopersicon esculentum) (viz. Toufan, Heinz and Bouzina). Irrigation with TWW persisted 15 days for the germination stage and 120 days for the growth and development stage. A control plot irrigated with a pure water (groundwater) was also set up in order to compare the seeds and the plants response to different concentrations of irrigation water. The final germination was expressed as a percentage of the total number of seeds in each treatment. This study has demonstrated that treated wastewater improves the germination in Heinz variety and had no effect on both Toufan and Bouzina varieties whether it is pure or diluted by half. For the growth stage, the statistical analysis showed that the Toufan variety has tolerated successfully the TWW irrigation with its high and moderate concentrations, and this by analysing all the morphophysiological parameters studied in this work (leaves numbers, stem and root length and dry biomass, relative water content and rate water loss)

Effect of nitrogen fertilizer on growth, flowering, fruiting and nodulation of three varieties of common bean in the arid region of aïn naga (Biskra, Algeria)

Field experiments were conducted to investigate the response of common bean (Phaseolus vulgaris L.) to nitrogen fertilizer. The main factor included the fertilizer (Granular Urea 46% N), was made up of two levels: no fertilization (0 kg/plot: control) and fertilization (0.4 kg/plot), while the secondary factor was the variety (three varieties of common bean: Djedida, Nelson and Jalila). The experimental design was a randomized complete block design with split plot arrangement and replicated four times. The effect of fertilization was evaluated during two development stages (flowering and fruiting) for each variety and this on the total dry biomass, the length of the aerial and root parts, as well as on the number of secondary roots. On the other hand, the combined effect of fertilization and variety was studied on some yield parameters per plant, such as the number of flowers, pods, seeds and the harvest index. In addition, the number of nodules at the end of seed maturation was evaluated. The results indicated that the nitrogen fertilizer application significantly reduced the root length, the number of nodules and secondary roots in most of the common bean varieties. However, fertilizer application significantly increased dry matter in both flowering and fruiting stages, for the three studied varieties. Pod number per plant and seed yield was increased by the application of N fertilizer, depending on varieties and the parameters being measured. Djedida and Jalila varieties gave the best yield and can therefore be recommended to farmers. According to our results, the percentage of improvement by N fertilization on one parameter or another does not exceed an average of 20%, compared to the control. Indeed, the effect of fertilization is positive and seems to increase the harvest index by 18% in Djedida and by 20% in Jalila, compared to non-fertilized plants. Unfertilized plants of the variety Nelson showed the highest ability to nodulate

Observer-based stabilisation of linear systems with parameter uncertainties by using enhanced LMI conditions

International audienceThis paper deals with the problem of observer-based stabilisation for linear systems with structured norm-bounded parameter uncertainties. A new design methodology is established thanks to a judicious use of some mathematical artefacts such as the well-known Young inequality and various matrix decompositions. The proposed method allows one to compute simultaneously the observer and controller gains by solving a single bilinear matrix inequality (BMI), which becomes a linear matrix inequality (LMI) by freezing some scalars. Furthermore, we show that some existing and elegant results reported in the literature can be regarded as particular cases of the stability conditions presented here. Numerical examples and evaluations of the conservatism are provided to show the effectiveness of the proposed design methodology

Optimization of Quartz Sand Leaching Process Using Design Experiments Method (DOE)

The present study aims at investigating the Algerian quartz sand from Djelfa deposit as a potential source to produce silicon. The sand from the Djelfa deposit has a high concentration but not enough to be used as raw material for pyrometallurgy (97%) of SiO2. Therefore, the quartz was treated using acid leaching process to increase the silica concentration up to 98.5%. Otherwise, we employ Design of Experiments Method Software (DOE) as numerical model to optimize the parameters of leaching and also to predict the etching behavior of sand grains during the primary step of the process. The results show that the effect of acid concentration has more influence than the grains particle sizes and leaching time to obtain the required silica purity. Using DOE numerical method in the first step of leaching, optimal response of purity (ΔP)(ΔP)\\left (\\mathrm \\\\Delta \ P\ \\right ) about 98.48% is obtained. In this context, the optimal grain sizes of sand and the optimal acid concentration are respectively, 276.9 \textmum and 21.15%, for 6 hours leaching time. The obtained response is very close to the experimental values and can be used for the next stage of the silicon production chain

Sand Dune Characterization for Preparing Metallurgical Grade Silicon

Dune sand, from Biskra, Algeria which is in the Great Algerian huge desert attracts tourists from all over the world. Dune sand composes around 80% of the total area of the desert. To date only a few studies have been conducted on this sand. The purpose of the present study is to shed light on the textural and physico-chemical characteristics of this sand using several characterization methods, and to understand the potential for using for photovoltaic applications. The chemical composition of Biskra sand indicated a high purity quartz with 97.6% silica, and a presence of others oxides. Granular analysis enabled the determination of the size of the sand grains which was found to be fine to medium. On the other hand, a Scanning Electron Microscopy and optical observations were carried out, the micrographs observations indicated the presence of different shapes of sand grain, some rounded whereas others are angular edged or elongated. X-ray diffraction indicates the highly crystalline nature of the Biskra sand